1、Designation:A720/A720M02(Reapproved 2016)1Standard Test Method forDuctility of Nonoriented Electrical Steel1This standard is issued under the fixed designation A720/A720M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of la
2、st revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEEditorially corrected designation in 2.1 in April 2016.1.Scope1.1 This test method covers determination of ductility uti-lizing Ep
3、stein test strips and a bending device for bending thestrip over a predetermined radius.It is intended for commercialsilicon-bearing steel sheet or strip of nonoriented types in thethickness range from 0.010 to 0.031 in.0.25 to 0.79 mm,inclusive.1.2 The values and equations stated in customary(cgs-e
4、muand inch-pound)or SI units are to be regarded separately asstandard.Within this test method,SI units are shown inbrackets.The values stated in each system may not be exactequivalents;therefore,each system shall be used independentlyof the other.Combining values from the two systems mayresult in no
5、nconformance with this test method.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitati
6、ons prior to use.2.Referenced Documents2.1 ASTM Standards:2A34/A34M Practice for Sampling and Procurement Testingof Magnetic MaterialsA677 Specification for Nonoriented Electrical Steel FullyProcessed TypesA683 Specification for Nonoriented Electrical Steel,Semi-processed TypesE290 Test Methods for
7、Bend Testing of Material for Ductil-ity3.Summary of Test Method3.1 A test strip is placed in the special test apparatusdesigned to clamp one end of the specimen securely while theother end is free to move,but held in tension by a spring.Thespecimen is repeatedly bent through 180 reversals until acra
8、ck appears at the bend or until sudden failure occurs bycomplete rupture.The number of reversals until failure is takenas a measure of the ductility.4.Significance and Use4.1 This is a specialized bend test for nonoriented electricalsteel not covered under the provisions of Test Methods E290.4.2 Thi
9、s test is applicable to nonoriented silicon steel suchas described in Specifications A677 and A683 in commercialthicknesses.4.3 It is not intended to be applied to steels consideredinherently ductile.5.Apparatus5.1 The apparatus,Fig.1,consists of a set of stationary jawsand a movable arm to which is
10、 attached another set of jaws anda spring.5.1.1 The stationary jaws shall have working edges withradii of approximately 0.2 in.5 mm over which the testspecimen is bent.Stationary jaws shall be of the quick-clamping type.5.1.2 The jaws attached to the movable arm shall allow thespecimen to move freel
11、y during bending.5.1.3 The spring clamped to the free end of the specimenshall provide sufficient tension in the specimen to localize thebend.5.1.4 Design of the movable arm shall permit a rotation ofapproximately 180.6.Sampling6.1 Select samples from at least two well separated loca-tions in each t
12、est lot or lift.6.1.1 The test specimens may be cut from samples used forthe core loss or other tests in accordance with the practice inPractice A34/A34M.1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of Subcommittee A06.01 on
13、 TestMethods.Current edition approved April 1,2016.Published April 2016.Originallyapproved in 1975.Last previous edition approved in 2011 as A720/A720M 02(2011).DOI:10.1520/A0720_A0720M-02R16E01.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at ser
14、viceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.1.2 Cut test specimens from near each end of each samplecoi
15、l and from the middle and the end of each sample sheet.7.Test Specimen7.1 The test specimens shall be about 1.2 in.30 mm inwidth and not less than 6 in.150 mm in length.7.2 The number of test specimens representing each test lotshall not be less than ten.7.2.1 The long axis of at least five test spe
16、cimens shall be inthe direction of rolling and at least five at right angles to thedirection of rolling.7.2.2 When width of the material prevents cutting speci-mens at right angles to the direction of rolling,all specimensshall be cut in the direction of rolling,and this shall be reportedwith the test results.7.3 Edges of the test specimens shall be practically free ofburrs;filing or machining to remove burrs is permissible.8.Procedure8.1 The specimen strips shall be at a temperature of 25 65C a
